Keisel, who is in the final year of his contract, has no plans to retire at season's end, and the reliable 34-year-old doesn't plan to let those emotions affect his play on the field either.

"I'm not saying it will be my last season," Keisel said. "I'm just saying it's the last year on my contract. That's all it is. I'm excited about this year, and we'll see what happens after that."

Age hasn't caught up to the energetic Keisel, who is playing the best football of his career. Keisel started 30 of the previous 32 games, finishing with 58 tackles and a career-best 40 quarterback pressures last year. He earned his first career Pro Bowl nod in 2010 and was named a third alternate the following year.

"I don't feel like age has bothered him at all," Steelers' linebacker Lawrence Timmons said. "Brett has been here for a long time and he provides energy to our defense. He has some type of youth juice."

The Steelers are in the process of instituting a youth movement on defense, revamping an aging veteran group that made three Super Bowl appearances and captured two championships. Several long-time members of those championship teams, vital to the Steelers' success, are gone. The list includes Aaron Smith, Chris Hoke, and James Farrior, in addition to Casey Hampton and James Harrison, who weren't retained in the offseason.

"It's a feeling that comes on later in your career where you know this could be your last year, it could be your last game," said Foote, who was also drafted in 2002, the same year as Keisel.

"You have to work that much harder, be that much more focused because you're trying to prolong your career as long as you can."

Keisel counts $4.5 million against the salary cap this year, and has 2011 first-round draft pick Cameron Heyward playing as his backup, a potential heir-apparent to the starting job at defensive end.

Keisel, the seventh-round draft pick out of BYU in 2002, is taking it in stride.

"I'm just enjoying it," Keisel said. "I enjoy being a leader, helping out some of these young guys, and still having the opportunity to play."

The young guys enjoy Keisel's veteran presence.

"He helps you play fast, helps you play hard, and helps you play smart," nose tackle Steve McLendon said. "Brett has two Super Bowls. We're trying to get where Brett is. We're trying to bring him number three."

Keisel plays a big brother mentor role to the other members of the defensive line, while also providing energy and a stabilizing presence following the recent losses of Hampton and Smith.

"We need his leadership and everything he provides to get us through," fifth-year defensive end Ziggy Hood said. "When we need answers we look for him. He's always going to provide words of wisdom. If he leads us through, I'm going to follow."

Keisel is unsure how his story will unfold. Another Super Bowl ring would provide the ideal ending, and he intends to do everything in his power to make sure that happens.

"I want to enjoy this year," Keisel said. "I don't know what's going to happen with everything. I'm going to go out and give it my all and have fun and see what happens.

"If this is the end, then I want to go out on top. If it's not the end, I'll be excited to be here."